> 这是我的代码：
> #include<iostream>
> #include<cstdio>
> #include<cstring>
> #include<queue>
> using namespace std;
> int m,n;
> int map[50][55];
> int sign[50][55][4];
> int direct[4][2]={{3,1},{0,2},{1,3},{2,0}};
> int f[4][3][2]={{{-1,0},{-2,0},{-3,0}},{{0,1},{0,2},{0,3}},
> {{1,0},{2,0},{3,0}},{{0,-1},{0,-2},{0,-3}}};
> struct node
> {
> 	int xi,xj;
> 	int step;
> 	int dir;
> }u,v,w;
> int si,sj,di,dj;
> int f2[4][2]={{0,0},{-1,0},{0,-1},{-1,-1}};
> void bfs(int e)
> {
> 	int i,j;
> 	int x,y;
> 	int k;
> 	queue<node>q;
> 	w.xi=si;
> 	w.xj=sj;
> 	w.step=0;
> 	w.dir=e;
> 	sign[si][sj][e]=1;
>     q.push(w); 
>     while(!q.empty())
>     {
>     	u=q.front();
>     	q.pop();
>     	//cout<<u.xi<<" "<<u.xj<<" "<<u.dir<<" "<<u.step<<endl;
>     	if(u.xi==di&&u.xj==dj)
>     	{
>     		printf("%d\n",u.step);
>     		return ;
>     	}
>     	bool check;
>     	for(i=0;i<3;i++)
>     	{
>     		check=false;
>     		v.xi=u.xi+f[u.dir][i][0];
>     		v.xj=u.xj+f[u.dir][i][1];
>     		v.step=u.step+1;
>     		v.dir=u.dir;
>     		if(v.xi<=0||v.xi>=m||v.xj<=0||v.xj>=n)break;
> 			if(sign[v.xi][v.xj][v.dir])break;
> 			if(map[v.xi][v.xj])break;
>     		for(j=0;j<4;j++)
>     		{
> 		        x=v.xi+f2[j][0];
> 		        y=v.xj+f2[j][1];
> 		       	if(x<0||x>=m||y<0||y>=n)
> 		       	{
> 		       		check=true;
> 		       		break;
> 		       	}
> 		       	if(map[x][y])
> 		       	{
> 		       	     check=true;
> 					 break;	
> 		       	}
>     		}
>     		if(check)break;
>     		sign[v.xi][v.xj][v.dir]=1; 
>     		q.push(v);
>     	}
>     	for(k=0;k<2;k++)
>     	{
>     		v.xi=u.xi;
>     		v.xj=u.xj;
>     		v.step=u.step+1;
>     		v.dir=direct[u.dir][k];
>     		if(sign[v.xi][v.xj][v.dir])continue;
>     		sign[v.xi][v.xj][v.dir]=1;
>     		q.push(v);
>     	}
>     }
>     printf("-1\n");
> }
> int main()
> {
> 	int i,j;
> 	int e;
> 	bool foud;
> 	while(scanf("%d%d",&m,&n))
> 	{ 
> 		if(m==0&&n==0)break;
> 		foud=false;
> 		for(i=0;i<m;i++)
> 		{
> 			for(j=0;j<n;j++)
> 			{
> 				scanf("%d",&map[i][j]);
> 			}
> 		}
> 		char s[20];
> 		scanf("%d%d%d%d",&si,&sj,&di,&dj);
> 		int x,y;
> 		for(j=0;j<4;j++)
> 		{
> 	        x=si+f2[j][0];
> 	        y=sj+f2[j][1];
> 	       	if(x<0||x>=m||y<0||y>=n)
> 	       	{
> 	       		foud=true;
> 	       		break;
> 	       	}
> 	       	if(map[x][y])
> 	       	{
> 	       	     foud=true;
> 				 break;	
> 	       	}
> 		}
> 		scanf("%s",s);
> 		if(strcmp(s,"north")==0)
> 		  e=0;
> 		else if(strcmp(s,"east")==0)
> 	      e=1;
> 	    else if(strcmp(s,"south")==0)
> 	      e=2;
> 	    else if(strcmp(s,"west")==0)
> 	      e=3;
> 		memset(sign,0,sizeof(sign));
> 	    if(si==0||si==m||sj==0||sj==n)
> 	    {
> 	    	foud=true;
> 	    }
> 	    if(di==0||di==m||dj==0||dj==n)
> 	    {
> 	    	foud=true;
> 	    }
> 	    if(!foud)bfs(e);
>         else printf("-1\n");
> 	}
> 	return 0;
> }